A typical vehicle seat includes a seat frame, a cushion pad (cushion material) attached to the seat frame, and a trim (surface cover) that covers the cushion pad. In recent years, a seat having an elastic sheet mounted to a seat frame in a tensioned state has also been developed (see JP 2014-94076 A). Using the elastic sheet, that has a cushioning property, the cushion pad can be made thin, which advantageously enables the whole seat to be made thin.
Meanwhile, a trim is usually fastened to the seat frame with a portion of the trim being stretched. Specifically, a wire of a pull-in cloth connected to a pull-in section of the trim is connected to a wire provided in the cushion pad with a hook ring (connecting attachment) (see JP 2001-61607 A).
The trim of a vehicle seat including such an elastic sheet as disclosed in JP 2014-94076 A is configured in a similar manner, but has a problem as described below. The structure disclosed in JP 2001-61607 A is suitable for a seat with a thick cushion pad which needs to be provided with a wire for the pull-in cloth, a wire for the seat frame, and a deep pull-in groove that accommodates the hook ring.
It is difficult to provide a deep pull-in groove in a seat having an elastic sheet that is provided to reduce the thickness of the cushion pad as disclosed in JP 2014-94076 A, so that it is disadvantageously difficult to pull in the trim with the trim being sufficiently stretched.
Instead of pulling in the trim, the trim and the elastic sheet may previously be sewed together to form a desired shape. However, sewing together the trim and the elastic sheet makes it difficult to attach the elastic sheet to the seat frame. For a seat designed to have an embedded heater or an embedded sensor, the trim should be designed for each seat design. There are further problems that, for example, once the elastic sheet is attached to the seat frame, the trim cannot be adjusted to flatten crimps.